Add extra column after db creation

[keyboard]

Lets say I have a db (mysql) that looks like this -

Username    Password    DateJoined

Bob         Pass        1/1/2012
Henry       Pass2       2/4/2012
Fred        Pass3       8/5/2012

But want it to look like this

Username    Password    DateJoined    LastLogin

Bob         Pass        1/1/2012      Val1
Henry       Pass2       2/4/2012      Val2
Fred        Pass3       8/5/2012      Val3

An example^

How would you add in the extra column?

[james438]

ALTER TABLE username ADD LastLogin TEXT NULL;

[keyboard]

Thanks James